The present invention relates to a semiconductor device to be used for mobile communication apparatuses (so called mobile phones) and to a technique for the manufacture thereof, particularly to a technique that is effective when applied to a semiconductor device to be mounted on an RF (Radio Frequency) power module.
In recent years, mobile communication apparatuses (so called mobile phones), which employ a communication system typified by GSM (Global System for Mobile Communications), PCS (Personal Communication Systems), PDC (Personal Digital Cellular) system or CDMA (Code Division Multiple Access) system, have gained widespread use throughout the world.
In general, such mobile communication apparatuses are each composed of an antenna for emitting and receiving electric waves, a high frequency power amplifier for amplifying power-modulated high-frequency signals and supplying them to the antenna, a receiver for processing high frequency signals received by the antenna, a controller for controlling them and a cell (battery) for supplying a power supply voltage.
Japanese Unexamined Patent Publication No. Hei 6(1994)-310717(Patent Document 1) discloses a technique for manufacturing a high voltage MOSFET having, on a drain side, a heavily doped drain region via a lightly doped offset drain region. The improvement is constituted by the fact that an impurity is ion-implanted into the sidewalls of a gate electrode twice, that is, before and after formation of sidewall spacers, to give an LDD (Lightly Doped Drain) structure to a source.
U.S. Pat. No. 6,020,611 discloses a technique for the manufacture of a high voltage MOSFET having, on a drain side, a highly doped drain region via a lightly doped offset drain region. The improvement here is constituted by the fact that a third drain region is formed between the lightly doped offset drain region and the highly doped drain region by twice performing ion implantation using photoresist films having different patterns as masks.    [Patent Document 1] Japanese Unexamined Patent Publication No. Hei 6(1994)-310717    [Patent Document 2] U.S. Pat. No. 6,020,611